Year | Value | 2022 | 1.5690738303958 | 2021 | 1.6583836794969 | 2020 | 1.7331295720599 | 2019 | 1.7940021254657 | 2018 | 1.8989307681473 | 2017 | 1.9897684946568 | 2016 | 2.0863028457394 | 2015 | 2.2052598068691 | 2014 | 2.3437930504114 | 2013 | 2.3157075035309 | 2012 | 2.2615873440311 | 2011 | 2.2076428106376 | 2010 | 2.0276396550843 | 2009 | 1.9561552223014 | 2008 | 1.958382903277 | 2007 | 1.9516743134829 | 2006 | 1.9466006406285 | 2005 | 1.983341437087 | 2004 | 2.0316656610188 | 2003 | 2.0878564619822 | 2002 | 2.0911032933169 | 2001 | 2.0564198428314 | 2000 | 2.0718347057799 | 1999 | 2.1133201570282 | 1998 | 2.1446270853591 | 1997 | 2.1554011942039 | 1996 | 2.155736503514 | 1995 | 2.1917228506576 | 1994 | 2.2450506741864 | 1993 | 2.2956311664186 | 1992 | 2.3240640928933 | 1991 | 2.411330333691 | 1990 | 2.5648085572032 | 1989 | 2.6665941595282 | 1988 | 2.7202166253373 | 1987 | 2.7182365303736 | 1986 | 2.737146758198 | 1985 | 2.7544412179276 | 1984 | 2.7550977467662 | 1983 | 2.7077568266867 | 1982 | 2.6138366012225 | 1981 | 2.5969678136079 | 1980 | 2.5842718504091 | 1979 | 2.5077513164512 | 1978 | 2.4328197849953 | 1977 | 2.3143188879173 | 1976 | 2.2276217946921 | 1975 | 2.2038554278877 | 1974 | 2.1575403049208 | 1973 | 2.1511827308143 | 1972 | 2.1556939048814 | 1971 | 2.2008437436421 | 1970 | 2.2858062128162 | 1969 | 2.3552253036218 | 1968 | 2.4271213471802 | 1967 | 2.4845476554364 | 1966 | 2.5458450765247 | 1965 | 2.6028899069283 | 1964 | 2.6344630199605 | 1963 | 2.6362218585468 | 1962 | 2.6219432895054 | 1961 | 2.6045181244264 |
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